I dont know if they make one for the Focus, but I bought one today for the Grand Prix to finish out a coolant flush to get rid of that crappy Dex-Cool. Most thermostats, when they fail or if the system overheats, will close thus stopping the flow of coolant and causing an overheating condition which you all know is a bad thing.
The MotorRad T-stat, if there is an overheat condition or if the t-stat fails it will open up and lock in the open condition so you still get coolant flow and probably by yourself a great deal of time to either get stopped or get somewhere so you can correct any problems with a much less chance of engine damage.
Obviously they are a little more pricey. I got a 180 degree t-stat and it cost me $11 I believe. Cheap protection in my mind. I thought about getting the 160 degree but I thought that would be too cool since the GTP will throw a CEL if it doesnt get up to temp in a certain time frame and Im pretty sure that would be an issue in the winter.